1. Field of the Invention
The present invention relates to a structure of a fluid passage output port of a fluid-operated apparatus formed with the fluid passage output port communicating with a fluid passage for introducing and discharging a fluid.
2. Description of the Related Art
The fluid pressure circuit has been hitherto constructed, for example, by connecting a tube to a fluid-operated apparatus such as a valve and a pump, for example, with a tube joint. A fluid passage for allowing the fluid to flow therethrough is formed at the inside of the fluid-operated apparatus. A fluid passage output port, which communicates with the fluid passage, is formed to protrude toward the outside. In this arrangement, the tube is directly connected to the fluid passage output port, or the tube is connected by the aid of the tube joint. Accordingly, the fluid passage of the fluid-operated apparatus is connected to make communication with a fluid passage of another fluid-operated apparatus.
FIG. 7 shows a structure of a fluid passage output port of a fluid-operated apparatus concerning the conventional technique.
As clearly understood from FIG. 7, the fluid-operated apparatus 1 includes a main body section 3 which has a fluid passage 2 formed at the inside. A pair of fluid passage output ports 4a, 4b, which protrude coaxially outwardly, are provided at a first end and a second end of the main body section 3. In this arrangement, the pair of fluid passage output ports 4a, 4b are formed integrally with the main body section 3.
In another arrangement, as shown in FIG. 8, the following structure is adopted. That is, first ends of fluid passage output ports 7a, 7b, each of which is formed to have a tube-shaped configuration, are inserted and fitted to holes 6 which are formed at the side surface of a main body section 5. The connecting portions between the insert portions of the fluid passage output ports 7a, 7b and the main body section 5 are welded with resin to form resin-welded sections 8. Thus, the both components are connected to one another.
However, in the case of the structure of the fluid passage output port of the fluid-operated apparatus concerning the conventional technique shown in FIG. 7, the main body section 3 and the fluid passage output ports 4a, 4b are formed in an integrated manner by means of the cutting machining. Therefore, an inconvenience arises such that burrs formed during the cutting machining are broken and fall, and any dust or the like is generated. Further, another inconvenience arises such that the deterioration of the surface roughness of the machined surface subjected to the cutting machining results in formation of recesses which behave as liquid pools.
In order to dissolve the inconveniences caused by the cutting machining as described above, a method is conceived, in which the main body section 3 and the fluid passage output ports 4a, 4b are integrally produced by means of the resin molding based on the use of a mold. However, other problems arise as follows. That is, it is difficult to produce the mold, because the fluid passage output ports 4a, 4b are lengthy. Further, the fluid passage output ports 4a, 4b formed with resin may be deformed, and the dimension accuracy may be deteriorated.
In the case of the structure of the fluid passage output port of the fluid-operated apparatus concerning the conventional technique shown in FIG. 8, the resin-welded section 8 possesses both of the function to avoid the leakage of the fluid flowing through the fluid passage and the function to prevent the fluid passage output port 7a, 7b from disengagement. Therefore, the following inconvenience arises. That is, the load is concentrated on the resin-welded section 8, resulting in occurrence of the shortage of the connection strength and the deterioration of the durability.
A general object of the present invention is to provide a structure of a fluid passage output port of a fluid-operated apparatus, which avoids the dust and the liquid pool with a simple mechanism, which has a sufficient connecting strength, and which makes it possible to improve the durability.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.